Voltage reference 732C

Overview
The Fluke Calibration 732C is a portable DC voltage reference standard providing 10 V, 1 V and 0.1 V outputs. The 734C is a rack‑width 4‑cell system that houses four electrically and mechanically independent 732C units for redundancy, comparison and reference transfer.

Key features

• Direct DC voltage reference designed for primary and secondary standards laboratories; RoHS compliant.
• Separate outputs at 10 V, 1 V and 0.1 V; no external dividers required for lower voltages.
• 734C: four independent 732C modules in a rack enclosure for redundant reference and secure transfer.
• Traceability to national standards and to Fluke Calibration 10 V Josephson Array.

Benefits and typical applications

• Redundancy and comparison: four‑unit architecture simplifies detection of drift and supports continuous reference availability.
• Portability: each 732C is compact (~5.91 kg) with internal battery (standard ≥72 hours; external battery option up to 210 hours) for on‑site calibrations and transfers.
• Compatibility: 734C supports combinations of 732B and 732C; units can be shipped hot or cold depending on operational needs.
• Use cases: primary lab reference maintenance, artifact calibration, on‑site transfer standards and device calibration support.

Model selection

• Base models: shipped cold (unpowered), standard stability characteristics as specified.
• Select/characterized models: shipped powered with drift characterization data; Select models demonstrate improved long‑term stability at 10 V.
• 734C configurations: 4‑cell Base and 4‑cell Select options available to match laboratory workflows.

Operation and maintenance

• Units may be shipped powered (“hot”) for continuous traceability or unpowered (“cold”) for standard shipment; select models include characterization data for drift prediction.
• Fluke Calibration offers calibration services traceable to national standards and the Josephson array to assign values and predicted performance for each 10 V output.
• Recommended use in controlled environments with good grounding and shielding for best performance.

Key specification tables
Line power (732C)
Line configuration | Accepted voltage | Accepted frequency
100 V | 90 V–110 V | 50 Hz / 60 Hz
120 V | 108 V–132 V | 50 Hz / 60 Hz
220 V | 198 V–242 V | 50 Hz / 60 Hz
240 V | 216 V–264 V | 50 Hz / 60 Hz

Stability (± µV/V)
Output | 30 days | 90 days | 1 year
10 V | 0.3 | 0.8 | 2.0
1 V | 0.6 | 1.2 | 3.0
0.1 V | 1.2 | 2.9 | 9.8

Select stability (Select models)
Output | 30 days | 90 days | 1 year
10 V | 0.3 | 0.8 | 1.0
1 V | 0.6 | 1.2 | 2.5
0.1 V | 1.2 | 2.9 | 8.0

Output noise (± µV/V, 0.01 Hz–10 Hz rms)
Output | S1 (± µV/V) | Sra (± µV/V) | Noise rms (µV/V)
10 V | 0.07 | 0.05 | 0.06
1 V | 0.16 | 0.14 | 0.15
0.1 V | 1.4 | 1.3 | 1.0

Output current and impedance
Output | Current limit | Output impedance
10 V | 12 mA (battery operation: total output current ≤0.1 mA recommended) | ≤1 mΩ
1 V | 1.2 mA | ≤1 mΩ
0.1 V | 20 pA | ≤100 Ω

Retrace/hysteresis for 10 V
Power‑off period | Change in 10 V output (± µV/V)
≤ 10 min | 0.1
10 min to 24 h | 0.25
24 h to 14 days | 0.25

Temperature coefficient (15 °C to 35 °C)
Output | Coefficient (± µV/V / °C)
10 V | 0.04
1 V | 0.1
0.1 V | 0.2

Altitude effect
Output | Change (± µV/V per 1000 ft / 305 m)
10 V | 0.05
1 V | 0.09
0.1 V | 0.18

Environment and mechanical (summary)
Operating: 15 °C to 35 °C; relative humidity 0%–90% at 28 °C (non‑condensing); altitude 0–1,830 m. Storage (battery removed): −40 °C to 50 °C; altitude 0–12,200 m. Insulation: resistance >10,000 MΩ; capacitance shunt <1000 pF. Safety: IEC 61010‑1 CAT II, pollution 2; IP20.

Usage notes

• For best performance use in temperature‑controlled, well‑grounded and shielded environments.
• Outputs may be shorted without damage; 10 V output protected against external voltages within specified limits.
• Use frequent comparisons among 734C cells to detect drift and maintain continuity of reference during transfers.

Technical characteristics (summary)

• Outputs: 10 V, 1 V, 0.1 V (separate binding posts referenced to VCOM).
• Battery: internal battery ≥72 hours (23 ±5 °C); charge time <36 hours; external battery option up to 210 hours; external DC input 12–15 V DC ≥300 mA.
• Dimensions 734C: H 17.8 cm × W 43.2 cm × D 50.3 cm (handles included); weight ≈30.4 kg. 732C: H 13.4 cm × W 9.8 cm × D 40.6 cm; weight ≈5.91 kg.
• Performance details: see stability, noise, temperature coefficient and altitude tables above.